Heretofore, a web offset printing press, as shown in FIG. 4, comprises a splicer infeed 1 for web feed and tension adjustment, for example, a 4-stage printing unit 2 for mono-or multicolor printing, a dryer 4, and a cooling drag 5 for cooling. The machine shown in FIG.1, further comprises first and second 2-stage folders, and the splicer infeed 1, the printing unit 2, the cooling drag 5, and the first and second folders 6 are driven by a motor 3.
In this printing press, a line shaft between the printing unit 2 and the dryer 4 is provided with a drive clutch 7, and the first and second folders 6 are also provided with folder clutches 7F. The drive clutch 7 is adjust starting under slow rotation, and the folder clutch 7F is adjust timing for phase matching between the printing unit 2 and the plate cylinder.
Timing of the folder clutch 7F is matched as follows. Since the plate cylinder makes one turn for two turns of a drive shaft of the motor 3, after tuning on the drive clutch 7, the folder clutch 7F is actuated in response to a pulse output from a detector 8 such as a limit switch for detecting two turns of the drive shaft by a pulse. Since there are two states (180.degree. rotation or 360.degree. rotation) in the rotational position of the plate cylinder, the folder 6 is set when it is actuated so that the folder clutch 7F is not actuated with a phase difference of half turn of the plate cylinder.
In practice, pulse output of the detector 8 of the drive clutch 7 and pulse output of the detector 8F of the folder clutch 7F are displayed on lamps on a control panel to detect a condition where the lamps simultaneously light.
A plurality of printing presses, for example, two of such a web offset printing press are disposed in parallel and operated in synchronization, and a printed matter is conducted to the folder of one printing press, thereby achieving a parallel synchronous operation method.
That is, one web offset printing press (hereinafter referred to as "machine A") as a main machine and the other web offset, printing press (hereinafter referred to as "machine B") as a sub-machine are linked by a new line shaft, and a clutch, specifically, the individual cooling drags 5 of the machine A and the machine B are connected with a line shaft and a clutch for synchronous operation to synchronize the machines A and B with each other, and webs printed by the both machines A and B are conducted to, for example, the folder 6 of the machine A to be folded.
Therefore, in parallel synchronous operation of the machines A and B, as described above, not only the folder clutch 7F must be actuated in synchronization with the phases of actuation of the drive clutch 7 and rotation of the plate cylinder, but also the drive clutch 7 for the rotation of the plate cylinder on the machine B is actuated, and then timing must be matched between the plate cylinder of the machine B and the plate cylinder and the folder of the machine A.
In the past, to connect -the machines A and B, after the actuation of the drive clutch 7 and the Folder clutch 7F of the machine A in slow operation and the drive clutch 7 of the machine B, operation of the machines was stopped, and a clutch for synchronous operation provided on the line shaft connecting the machines A and B while matching the timing was manually connected so that phases of the plate cylinders of the machines A and B were matched with each other, or the phase of the plate cylinder of the machine B was matched with t, he phase of the folder 6 of the machine A, or a synchronous operation electromagnetic clutch was connected while individually matching the timing on the individual control panels of the machines A and B.
However, such manual connection or connection on the individual control panels of the individual clutches for synchronous operation while matching the timing of the machines A and B is a tedious work and a burden to the operator.
A primary object of the present invention is to provide a method and apparatus for parallel synchronous operation of weld offset printing presses which enables exact phase matching by a simple operation with a reduced burden to the operator.